Machines for paving concrete



` Jan. 20, 1970 M; McGREGoR ETAL 3,490,346

MACHINES FOR PAVING CONCRETE Filed sept. 11, '1967 2 sheets-sheet 1 FIG. 7.

INV E me@ MATTAf- VAHC Csascfoa Jan. 20, 1970 M. MccsREGoFe ETAL MACHINES FOR PAVING CONCRETE 2 Sheets-Sheet B Filed Sept. ll, 1967 INV ENT@ R5 MTYH EW MCREGR mi@ Emma@ @o mg mf i7@ United States Patent Office 3,490,346 Patented Jan. 20, 1970 3,490,346 MACHINES FR PAVING CONCRETE Matthew McGregor and Albert E. Burks, Chesterfield,

England, assgnors to Robert McGregor & Sons Limited, Chesterfield, England, a British company Filed Sept. 11, 1967, Ser. No. 666,603 Claims priority, application Great Britain, Sept. 16, 1966, 41,492/ 66 Int. Cl. E01c 19/48, 19/30 U.S. Cl. 94-46 6 Claims ABSTRACT oF THE DISCLOSURE A concrete paving machine comprising at its front side a conforming plate which, as the machine advances, levels preplaced plastic concrete and, in advance of said plate, concrete compacting means consisting of at least one transversely extending member which is vibrated axially and which has horizontal or inclined plates projecting laterally therefrom.

This invention relates to machines for laying concrete in the construction of roads and like paved surfaces.

Concrete paving machines arey known incorporating concrete levelling and compacting means comprising a forming plate which, as the machine advances, levels plastic concrete preplaced in front of the machine, and a series of poker vibrators arranged across the width f the machine and extending in the direction of travel and into the plastic concrete.

Such machines produce concrete of varying degrees of compaction, there being a tendency for the density to fall oif beyond a radius of about 7" from the centre of each poker vibrator. The devices are also liable to create a pattern of surface irregularity in a reinforced pavement, corresponding to the pattern of the reinforcing material.

Furthermore, the poker vibrators are only able to compact concrete whose workability exceeds about 1/2" slump. If concrete is less workable than this, i.e., if it is in general drier than this condition, there is a real risk of the poker vibrators over-heating and becoming permanently unserviceable, since they rely on the wetness 0f the concrete for their cooling. Similarly, the tube vibrator is liable to suffer breakdown of the bearings due to overheating in too dry concrete. Moreover, if the maximum size of aggregate is greater than about 2", there is a risk of stones becoming jammed between the front of the conforming plate and the tube vibrator, causing distortion of the vibrator and excessive loading of the bearings. This has been known to result in failure of the bearings.

If any of the failures described occur in the course of normal concreting, expensive delays ensue, due to the diiculty of removing sufficient concrete to allow access to the faulty component.

The present invention aims to provide a concrete paving machine which overcomes the aforementionad disadvantages.

According to the invention a concrete paving machine is provided with concrete compacting means comprising at least one vibrated member extending transversely or substantially transversely across the width of the machine in front of a forming plate and having a number of spaced horizontal or inclined plates fixed thereto and projecting laterally therefrom.

Preferably, two such vibrated members, in the form of tubes or girders and arranged one in advance of the other, are employed, said members being carried by common supporting means and the required vibration being effected by imparting axial reciprocation or oscillation to the members, this reciprocation being 180 out of phase in the two members such that end thrusts on the supporting means balance out. These and other features of the invention will be more fully understood from the following description of a preferred embodiment, reference being made to the accompanying drawings wherein FIG. 1 is a front view of the improved compacting means,

FIG. 2 is a fragmentary plan view of FIG. 1, and

FIG. 3 is a side view of said compacting means to an enlarged scale.

In the drawings there is shown the leading portion of a concrete laying machine of the type known as a slip -form paver and which leading portion is defined by a forming plate 1, plastic concrete being delivered in advance of the paver as indicated at 2 and the concret being levelled in known manner by the forward movement of the paver to create a layer 3 of predetermined depth upon the base 4.

For the purpose of compacting the concrete there is provided in the present instance two vibrating units arranged one in advance of the other in front of the forming plate, each unit consisting of a horizontal steel tube 5 extending transversely across the full width of the machine in a position where it is submerged by the concrete being delivered to the base, and a series of rectangular steel plates 6 welded to the tube at spaced intervals and extending laterally therefrom. In the drawings, the

' plates 6 are shown at an angle of 45 to the horizontal but they may extend at any other desired angle or com` pletely horizontal. The vibrating units are suspended at their ends and at one or more intermediate points by means of brackets 7 from triangulated beam structures 8, said brackets incorporating resilient shock absorbing blocks or bushes 7a and the beam structures also being attached to the paver by means of shock absorbing mountings 9 thereby preventing the vibrations of the units being transmitted to the body of the paver.

The units may be vibrated by any appropriate means, the arrangement shown comprising eccentrios 10 connected to the tubes 5 by pivot end 11a of connecting rods 11 and being themselves driven by an electric motor 12 through belt and pulley gearing 13 or equivalent means. The axial oscillation or vibration thus imparted to the tubes may have a frequency within the range of 3000- 7000 per minute and an amplitude of up to 0.1 inch and preferably around 0.06 inch, this large amplitudeof oscillation ensuring full compaction of all of the concrete passing through the machine. Furthermore, the two eccentrics 10 are 1807 out of phase whereby any axial thrusts transmitted to the beam structures 8 cancel out and so are not transmitted to the body of the machine.

yIn the drawings, vibrating means are shown at one end only of the tubes but, if desired, similar means may also be provided at the other end of the tubes, thisgconstruction having the advantage that is is possible to pull the tubes in both directions thus avoiding the risk of possible buckling of the tubes which might arise when displacing a long tube through plastic concrete solely by thrust. It ywill be appreciated that where vibrating means are provided at both ends of the tubes, such means must be synchronised and this is preferably effected by mechanical linkage between the driving gears or driving motors.

The machine according to the invention possesses the additional advantage that it can compact concrete whose workability ranges from zero slump, i.e., significantly drier than is possible with existing paving machines. Hence for the same cement content much stronger concrete can be obtained.

It is believed that the irregularity of the surface referred to above is caused by compression waves passing longitudinally along the steel reinforcement members. Since the machine according to the inven-tion produces vibrations only in the transverse vertical plane, this cause will be removed and no irregularity in the concretepaving will be experienced. Furthermore, the machine according to the invention is able to work in free air without damage to said machine or detrimental effect to the concrete paving. f

It will thus be seen that the slip form paving machine according to the present invention possesses great advantages over prior machines and represents a distinct improvement thereon.

We claim:

1` A concrete paving machine having a forming plate forwardly of which uent concrete is delivered, and concrete compacting means comprising two suspended transverse members disposed to be at least partially submerged in said concrete being delivered, and means for separately axially vibrating said members in predetermined out of phase sequence.

2. 1n the paving machine dened in claim 1, said mem bers being carried on a common support in substantially parallel relation and said vibrating means being `about 180 out of phase soy that end thrusts on the support are effectively canceled.

3. In the paving machine dened in claim 1, said vibration means comprising a rotating drive eccentric mounted adjacent an end of each tube on an axis normal to said each tube, and a connecting rod substantially aligned with and having one end pivotally connected to said one end of each tube, the other end of said rod connected to said eccentric to impart axial vibration to said each tube.

4. A concrete paving machine having a relatively xed forming plate forwardly of which liuent concrete is delivered, and concrete compacting means comprising a transverse member ilexibly supported with respect to said plate, means for vibrating said member comprising a power driven eccentric rotatable on an axis substantially normal to said member and operably drive connected to said mem-ber to impart axial vibration to said member, and a series of vertically inclined plates secured upon said member, said member and said plates adapted to be at least partially submerged in said uent concrete.

5. In the concrete paving machine dened in claim 4, means defining al frame having shock absorbing means by which said transverse mem-ber is mounted thereon, and further shock absorbing means between said frame and said machine. v

6. In the concrete paving machine defined in claim 4, there being similarl synchronized eccentrics connected to opposite ends'of said transverse member.

References Cited UNITED STATES PATENTS 2,259,110 10/ 1941 Jackson 94-48 2,261,766 11/1941 Jackson 94-48 XR 2,269,1 10 1/ 1942 t Jackson 94-48 2,332,687 l/ 1943 Baily. 3,098,415 7/ 1963 Guntert 94-46 3,135,178 l 6/1964 Guntert 94-46 IACGB L. NACKENOFF, Primary Examiner US. Cl. X.R. -94-48 

